Gas turbine engine

ABSTRACT

A gas turbine engine is provided having a variety of forms and features. The gas turbine engine can include a compressor having movable vanes. In one form of operation the compressor can close down the vanes to a relatively low flow capacity position and the compressor can be operated at a higher speed, whereupon the vanes can be repositioned and the gas turbine engine operated at a different condition. The gas turbine engine can include a turbine having movable vanes. In one form of operation the turbine can change the vane positions to a relatively low torque position and the engine operated at a higher fuel flow condition, whereupon the vanes can be repositioned and the gas turbine engine operated at a different condition. The gas turbine engine can have a heater that adds heat to a flow stream, a motor that provides energy to a shaft, and an external load.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication 61/204,003, filed Dec. 31, 2008, and is incorporated hereinby reference.

FIELD OF THE INVENTION

The technical field relates to gas turbine power systems and methods toachieve power changes.

BACKGROUND

Providing the ability to change gas turbine engine power configurationremains an area of interest. Unfortunately, some existing systems havevarious shortcomings relative to certain applications. Accordingly,there remains a need for further contributions in this area oftechnology.

SUMMARY

One embodiment of the present invention is a unique gas turbine engine.Other embodiments include apparatuses, systems, devices, hardware,methods, and combinations for changing a configuration associated with agas turbine engine. Further embodiments, forms, features, aspects,benefits, and advantages of the present application shall becomeapparent from the description and figures provided herewith.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts one embodiment of the present application.

FIG. 2 depicts one embodiment of the present application.

FIG. 3 depicts one embodiment of the present application.

FIG. 4 depicts one embodiment of the present application.

FIG. 5 depicts one embodiment of the present application.

FIG. 6 depicts one embodiment of the present application.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

With reference to FIG. 1, a gas turbine engine 50 is shown having acompressor 52, a combustor 54, and a turbine 56, which together may beused as an aircraft power plant. The gas turbine engine 50, as well asthe other gas turbine engines designated in this application withsimilar reference numbers ending in ‘50’, can take a variety of formssuch as, but not limited to, a turbofan, turbojet, turboshaft, andturboprop. In fact, any of the various features of the various gasturbine engines discussed below are also contemplated for use in avariety of combinations in any of the other of the gas turbine engines.As used herein, the term “aircraft” includes, but is not limited to,helicopters, airplanes, unmanned space vehicles, fixed wing vehicles,variable wing vehicles, rotary wing vehicles, hover crafts, and others.Further, the present inventions are contemplated for utilization inother applications that may not be coupled with an aircraft such as, forexample, industrial applications, power generation, pumping sets, navalpropulsion and other applications known to one of ordinary skill in theart. As will be appreciated, the present inventions can be used in avariety of platforms or mobile vehicles, whether or not including theaircrafts described above.

Airflow 58 enters the gas turbine engine 50 and is compressed by thecompressor 52 before entering the combustor 54 where it is mixed withfuel and burned before being expanded by the turbine 56. A rotatingshafting 60 connects the turbine 56 to the compressor 52 and serves totransfer power between the two. As will be appreciated, the rotatingshafting 60 can include more than one shaft. Though the illustratedembodiment depicts an axial flow gas turbine engine, centrifugalcompressors and/or turbines may also be incorporated in some alternativeembodiments.

The gas turbine engine of the illustrated embodiment includes twoseparate engine spools, which term is sometimes used to indicate thecombination of a compressor section, a shaft, and a turbine section. Insome applications, however, a spool may not include a correspondingcompressor, as will be described below. The spools are generallyreferred to as a high pressure (HP) spool and a low pressure (LP) spool.The HP and LP spools are free to rotate at different speeds, althoughdevices, either mechanical, electrical, or otherwise, may transfer powerfrom one shaft to the other. Though the illustrated embodiment depictsspools having shafts that share a common centerline, in some embodimentsthe spools may include shafts that do not share a common centerline. TheHP spool includes a high pressure compressor, a high pressure shaft, anda high pressure turbine which are sometimes denoted as an HP compressor,an HP shaft, and an HP turbine, respectively. Likewise, the LP spoolincludes a low pressure compressor, a low pressure shaft, and a lowpressure turbine which are sometimes denoted as an LP compressor, an LPshaft, and an LP turbine, respectively. Some embodiments, however, mayhave a low pressure spool without a corresponding compressor, such aswould be the case with a turboshaft engine having a free turbineconnected directly to a helicopter main rotor, for example. In stillother embodiments, the gas turbine engine may include additional spoolsthan those depicted in the illustrated embodiment, such as anintermediate spool to set forth just one non-limiting example.

The compressor 52 includes a low pressure compressor 62 and a highpressure compressor 64 which are each connected to the shafting 60. Inparticular, the low pressure compressor 62 is connected to a lowpressure shaft 66, and the high pressure compressor 64 is connected to ahigh pressure shaft 68. Other shafts may be included in otherembodiments such that the shafting 60 includes more than two shafts.Although not depicted in the illustrated embodiment, other embodimentsmay include a gearbox or other device between the compressor and turbineof a given spool such that the compressor and turbine rotate atdifferent speeds. The compressor 52 includes a bleed 69 and inlet guidevanes 76 in the illustrated embodiment, but other embodiments may lacksuch features. In addition, some embodiments of the compressor 52 caninclude an offtake passage, either separately or in addition to anyother features described herein. Each of the low pressure compressor 62and the high pressure compressor 64 include a series of vanes, denotedas low pressure vanes 72 and high pressure vanes 74 a, 74 b, and 74 c,respectively. The compressor 52 may include more compressor sectionsincluding, but not limited to an intermediate compressor section and afan section, to set forth just two non-limiting examples.

Each of the low pressure compressor 62 and the high pressure compressor64 has a number of compression stages shown in the illustratedembodiment. In some embodiments, the number of compression stages may begreater than or less than the number of stages depicted in theillustrated embodiments. As will be understood, each compression stageincludes a row of rotating compressor blades followed by a vane. Forexample, the low pressure compressor 62 includes three rows of rotatingblades 78 each followed by a row of independently variable low pressurevanes 72. Likewise, the high pressure compressor 64 includes three rowsof rotating blades 80 each followed by a row of independently variablehigh pressure vanes 74 a, 74 b, and 74 c.

Each row of blades 78 in the low pressure compressor 62 rotate at a samespeed about a centerline L of the gas turbine engine 50, just as do eachrow of blades 80 in the high pressure compressor 64. However, the highpressure compressor blades 80 may not rotate at the same rate as the lowpressure compressor blades 78. One or more rotors associated with eitheror both blades 78 and 80 can be capable of contra-rotation relative torotors associated with other of the blades. If any of the rotors arecapable of contra-rotation, some of the vanes may not be needed. Neitherthe variable inlet guide vanes 76 nor the vanes 72, 74 a, 74 b, and 74 crotate about centerline L. Rather, the inlet guide vanes 76 and thevanes 72, 74 a, 74 b, and 74 c are fixed relative to their centerlinebut are capable of rotating to an angle relative to the airflowtraversing the compressor 52, as will be understood by those in the art.In some forms, however, one or more of the vanes 72, 74 a, 74 b, and 74c may be fixed and not capable of rotating to an angle relative to theairflow traversing the compressor 52.

For each set of high pressure vanes 74 a, 74 b, and 74 c that arecapable of being rotated relative to the airflow, each vane in the rowrotates to a common angle which is defined relative to the centerline ofthe vanes. The vanes 74 a, 74 b, and 74 c can be rotated via anysuitable mechanism including a single hydraulic piston configured torotate a set of rings that encircle the high pressure compressor 64,where there is at least one ring for each vane row. Each of the vanes 74a, 74 b, and 74 c is connected to its ring or rings by levers. Therotation of the rings causes the levers to move thus providing therotation of the vanes. Other mechanisms of rotating the vanes are alsocontemplated herein. Each vane row 74 a, 74 b, and 74 c is independentlyvariable relative to each other row. For example, the common angle invane row 74 a need not be the same as the common angle in vane row 74 b.In some applications the vane rows need not be independently variable.In some embodiments, one or more of vane rows 74 a, 74 b, and 74 c maybe fixed and not capable of rotating to a common angle. However, it iscontemplated herein that at least two rows of vanes 74 a, 74 b, and 74 care independently variable. In some embodiments, a full authoritydigital engine controller (FADEC) may be used to independently vary orotherwise schedule the vanes 74 a, 74 b, and 74 c. Each angle of thevanes 74 a, 74 b, and 74 c relative to the airflow traversing throughthe compressor 64 is denoted as α, and the set of angles for vane rows74 a, 74 b, and 74 c is denoted as a boldface α. The vanes 74 a, 74 b,and 74 c can be rotated to a set of angles α to restrict the airflowtraversing through the high pressure compressor 64 relative to anon-restricted condition, which will be described further hereinbelow.

The bleed 69 is configured downstream of the second stage in the highpressure compressor 64 and includes a first conduit 75 a, a secondconduit 75 b, and a valve 77. Other configurations of the bleed 69 arealso contemplated. The bleed 69 is configured to remove, or bleed, airfrom the flow traversing through the high pressure compressor 64. Theairflow that is bled from the high pressure compressor 64 through thebleed 69 can be routed elsewhere in the gas turbine engine 50, oralternatively may be vented overboard. Although the bleed 69 isconfigured downstream of the second stage in the high pressurecompressor 64, other embodiments may locate the bleed 69 elsewhere inthe gas turbine engine 50. In addition, the gas turbine engine 50 mayinclude more than one bleed 69, either arranged at the same axialstation downstream of the second stage, at least in the illustratedembodiment, or may be configured elsewhere in the engine.

The valve 77 is configured to remove air at a variable rate from thehigh pressure compressor 64, and may also be shut off such that no airis removed. Various types of valves are contemplated for use as thevalve 77, such as a shut off valve, a throttling valve, or a split flowvalve, to set forth just a few non-limiting embodiments. The valve 77may be either manually or automatically actuated, such as through theuse of a FADEC or an operator input.

The inlet guide vanes 76 include a row of vanes that may be used inconjunction with the variable high pressure vanes 74 a, 74 b, 74 cand/or the bleed 69 to restrict air flow through the gas turbine engine50. Although the inlet guide vanes 76 are depicted upstream of the lowpressure compressor 62, other embodiments may arrange the inlet guidevanes 76 upstream of the high pressure compressor 64, such as can be thecase in a turboshaft engine, to set forth just one non-limiting example.As described above, as the airflow is decreased, fueling to thecombustor 54 is adjusted to offset any corresponding change in speed ofthe high pressure compressor 64. The inlet guide vanes 76 can be rotatedto a position independent of the variable high pressure vanes 74 a, 74b, and 74 c.

The turbine 56 includes a low pressure turbine 84 and a high pressureturbine 82, each of which are connected to corresponding shafts denotedas the low pressure shaft 66 and the high pressure shaft 68. The lowpressure turbine 84 and the high pressure turbine 82 can rotate at thesame rate as the corresponding low pressure compressor 62 and the highpressure compressor 64, respectively. In some non-limiting forms a gearor gearbox can be coupled between respective turbines and compressors.

The high pressure turbine 82 includes a single stage having a row ofvanes 86 followed by a row of blades 88. The high pressure turbine 82may include additional stages in other embodiments. The vanes 86 arecapable of rotating to an angle with respect to the airflow traversingthe high pressure turbine 82, but do not otherwise rotate about thecenterline L. In some forms the vanes 86 can be fixed. The blades 88, onthe other hand, do rotate about their centerline but do not otherwiserotate in the same manner as the vanes 86, as will be appreciated bythose skilled in the art. Though not depicted, a row of turbine outletguide vanes may be included in some embodiments.

The low pressure turbine 84 includes two stages of low pressure turbinevanes 90 and blades 92. In some embodiments, the low pressure turbine 84may include either fewer or more stages. In some forms one or morerotors associated with either or both blades 88 and 92 can becontra-rotatable relative to other of the rotors. In some applicationsone or more vane rows may not be needed if any of the rotors arecontra-rotatable. Though not depicted, a turbine outlet guide vane maybe included in some embodiments. Each row of vanes 90 may beindependently movable or may move together. It will be understood hereinthat any given turbine stage throughout the gas turbine engine 50 may beconfigured as either an impulse turbine stage or a reaction stage,depending on the needs of a given application.

The operation of the gas turbine engine 50 and various other embodimentsproceed as follows. Consider operating condition “A” in which relativelylittle LP turbine torque, T_(A), is transmitted to the LP shaft 66, andthe variable high pressure vanes 74 a, 74 b, and 74 c are set at anglesthat approximately optimize the HP compressor efficiency. Designate thisset of vane angles collectively as α_(A). Designate the rotational speedof the HP spool as NHP_(A). Now consider operating condition “B” inwhich more LP turbine torque, T_(B), is transmitted to the LP shaft thanin condition “A” (T_(B)>T_(A)). Suppose again that the variable highpressure vanes 74 a, 74 b, and 74 c are set at angles α_(B) thatapproximately optimize the HP compressor efficiency, and that the speedof the HP spool consequently is NHP_(B). The discussion herein assumesthat sustained high torque transfer from the LP turbine to the LP shaftrequires a higher HP spool rotational speed than is required for lowtorque transfer to the LP shaft. Therefore, NHP_(B)>NHP_(A).

If the gas turbine engine 50 is operating at condition “A” to produceT_(A), but a rapid transition to condition “B” to produce T_(B) isanticipated, the following sequence of events can occur to achieve thetransition. Before the transition from T_(A) to T_(B) occurs, the HPcompressor variable vane angles α_(A) are controlled from α_(A) so as toreduce the flow capacity of the compressor at a given speed. Engine fuelflow is simultaneously controlled, however, to maintain torque T_(A)transmitted by the LP turbine to the LP shaft. The result is that the HPspool rotates faster than NHP_(A) to produce the gas flow required todrive the LP turbine to produce torque T_(A). During the transition fromcondition “A” to a standby condition, the variable vanes and the enginefuel flow, and perhaps other factors such as operation of the bleed 69,or rotation of the inlet guide vanes 76, or rotation of vanes 86, arecontrolled together until the HP spool speed reaches NHP_(B) (or as nearas stress considerations or other operational limits will allow) but theLP turbine still transmits only torque T_(A) to the LP shaft. Once theengine settles into a steady state, the engine can be considered to bein a standby mode for condition “B”, with the HP compressor variablevane angles having values collectively designated α_(standby). When thetransition from T_(A) to T_(B) is required, the HP compressor variablevane angles are rapidly transitioned from α_(standby) to angle set α_(B)while the fuel flow and any other controlled engine parameters areadjusted as required to achieve condition “B”. This transition fromT_(A) to T_(B) can be accomplished rapidly because the HP spool isalready rotating at or near its required speed. The procedure can bereversed when a rapid decrease in power, as from T_(B) to T_(A), isrequired.

FIG. 2 depicts an embodiment of the gas turbine engine 50 of FIG. 1configured to provide power to an external load 94 through a generator93. In one application the external load 94 can take the form of adirected energy weapon 94. In this embodiment, the gas turbine engine 50is configured as a turboshaft engine and has only the HP compressor 64,the combustor 54, the HP turbine 82, and the LP turbine 84. Other typesof gas turbine engines, other than a turboshaft, can also be utilized todrive the directed energy weapon 94. In addition, other embodiments mayinclude more spools than the LP and the HP spools depicted in FIG. 2. Itshould be appreciated that the discussion that below regarding thedirected energy weapon 94 in FIG. 2, as well as discussions that followregarding other directed energy weapons with respect to the otherfigures, is intended for illustration purposes only and does nototherwise limit the scope of the external load, of which the directedenergy weapon is but one example. To set forth just one additionalnon-limiting example, in some applications the external load could be asource of direct mechanical power absorption such as a propeller orhelicopter rotor.

The generator 93 is coupled to the LP shaft 66 of the gas turbine engine50 and provides electrical power to the directed energy weapon 94 uponrotation of the LP shaft 66. The generator 93 and/or associatedelectronics is capable of producing any form of electrical power,whether direct current (DC) or alternating current (AC). Furthermore,the generator 93 may be driven by any shaft of the gas turbine engine50, not just via the LP shaft 66 as depicted in the illustratedembodiment. The generator 93 may provide a range of power at a varietyof rotational speeds of the LP shaft 66. A controller can be provided toset the LP shaft 66 at a constant rotational speed. Though not depictedin the illustrative embodiment, other mechanical devices such as gearingor a clutch assembly may be provided between the generator 93 and the LPshaft 66.

The directed energy weapon 94 receives electrical power provided fromthe generator 93 and converts it to radiant electromagnetic energyoutput. An antenna or other radiator may be included in the directedenergy weapon 94 to provide for the radiant energy output. In one form,the directed energy weapon 94 is a form of a gyrotron that generates adirected, radiant electromagnetic output in the microwave range. Inother forms, the directed energy weapon 94 may be based on a form oflaser, such as a free electron laser, that may extend from the microwaveregime to the visible light spectrum. The directed energy weapon 94 mayalso be a combination of different radiant energy generators.

In one form the operation of the embodiment depicted in FIG. 2 proceedsas follows. The two-spool turboshaft gas turbine engine 50 is used toprovide electrical power for the directed energy weapon 94 by drivingthe electrical generator 93 connected to the LP spool. A controller (notshown) for the generator 93 maintains an approximately constantmechanical rotation speed for the LP shaft 66. In alternativeembodiments, however, the controller need not maintain a constantmechanical rotation speed. At idle power and therefore low output torqueof the LP turbine 82, no net electrical power is produced by thegenerator 93, and the HP spool rotates at a relatively low speedcompared to its design point. In some embodiments, however, thegenerator 93 may produce electrical power at the engine idle condition.Before the directed energy weapon 94 is to be energized, the gas turbineengine 50 is placed in a standby mode, which can occur at any time suchas, but not limited to, a few seconds before the directed energy weapon94 is to be energized. The generator 93, the engine fuel flow to thecombustor 54, and the angle of the variable high pressure vanes 74 a, 74b, and 74 c are controlled together to produce an HP spool speedcorresponding to full power operation while producing only low outputtorque of the LP turbine 82 and therefore idle power to the electricalgenerator 93. In other embodiments, the bleed 69 and/or an inlet guidevane (not shown) may be operated in conjunction with the engine fuelflow and the variable high pressure vanes 74 a, 74 b, and 74 c. Othercomponents and/or parameters can be used in addition or alternative tothe components and/or parameters listed herein. Furthermore, a varietyof combinations of the components and/or parameters can be used, and notstrictly the groupings listed above. To energize the external load 94,which in the illustrated embodiment is the directed energy weapon 94,the variable high pressure vanes 74 a, 74 b, and 74 c are moved to theirdesign value to produce a greater amount of torque output of the LPturbine 82, while electrical power required for operation of thedirected energy weapon 94 is drawn from the generator 93. The fuel flowis adjusted as required to maintain the power required by the generator93. To de-energize the directed energy weapon 94, the electrical powerdrawn from the generator 93 is interrupted, the variable high pressurevanes 74 a, 74 b, and 74 c are moved to their standby position, and thefuel flow is adjusted as required to maintain a constant HP spool speed.To return the engine to idle, the fuel flow is varied and the angle ofthe variable high pressure vanes 74 a, 74 b, and 74 c are adjusted untilthe normal idle configuration is achieved.

Turning now to FIG. 3, an embodiment of a gas turbine engine 150 isshown having the capability to produce rapid changes in turbine outputtorque through the use of independently variable turbine vanes. The gasturbine engine 150 includes a compressor 152, a combustor 154, and aturbine 156. Airflow 158 is compressed by the compressor 152 and isburned with fuel in the combustor 154 before being expanded by theturbine 156. The compressor 152 and the turbine 156 are connected via ashafting 160, which includes a low pressure shaft 166 and a highpressure shaft 168. Though the illustrative embodiment is depicted as anaxial flow gas turbine engine 150, other configurations are alsocontemplated. To set forth just one example, airflow may enter, say, aturbine of the illustrative embodiment in either primarily an axialdirection or from a primarily radial direction, or from any otherdirection. In one non-limiting embodiment, the turbine 156 may include aradial inflow turbine followed by an axial flow turbine, to set forthjust one non-limiting example.

The compressor 152 includes a low pressure compressor 162 and a highpressure compressor 164, each of which contain a number of compressionstages. In other embodiments, the number of stages may be different thanthe numbers depicted in FIG. 3. The low pressure compressor 162 includesthree stages of compressor blades 178 and vanes 172. The vanes 172 maybe individually fixed or may be capable of rotating relative to theairflow traversing the low pressure compressor 162. The angle ofrotation of the vanes 172 may vary from stage to stage.

The high pressure compressor 164 includes three stages of compressorblades 180 and vanes 174. Just as in the low pressure compressor 162,the vanes 174 in the high pressure compressor 164 may either beindividually fixed or may be capable of rotating relative to the airflowtraversing the high pressure compressor 164. The angle of rotation ofvanes 174 may vary from stage to stage.

The turbine 156 includes a high pressure turbine 182 and a low pressureturbine 184 which are connected to the corresponding compressors 164 and162 via the high pressure shaft 168 and the low pressure shaft 166,respectively.

As set forth in the illustrative embodiment, the HP turbine 182 in theillustrated embodiment has a single turbine stage, while the LP turbine184 has two turbine stages. In some embodiments, the number of turbinestages may be greater than the single stage depicted in the HP turbine182 of the illustrative embodiment, or greater than or less than thenumber of stages depicted in the LP turbine 184. As will be understood,each turbine stage includes a row of vanes followed by a row of rotatingturbine blades. For example, the HP turbine 182 includes a row of vanes186 followed by a row of rotating blades 188. The LP turbine 184, on theother hand, includes two rows of independently variable vanes 190 a and190 b each followed by two rows of rotating blades 192.

Each vane in a row of the LP turbine variable vanes 190 a and 190 b arecapable of being rotated to a common angle which is defined relative tothe centerline L, much like the independently variable high pressurevanes 74 a, 74 b, and 74 c of FIGS. 1 and 2. In addition, each vane row190 a and 190 b is independently variable relative to each other row.For example, the common angle in the vane row 190 a need not be the sameas the common angle in the vane row 190 b. In some embodiments, one ofthe vane rows 190 a and 190 b may be fixed and not capable of rotatingto a common angle. In those embodiments with more than two stages, anynumber of rows of vanes can be fixed provided at least one row iscapable of rotating to a common angle. In some embodiments, a fullauthority digital engine controller (FADEC) may be used to independentlyvary or otherwise schedule the vanes 190 a and 190 b. Each angle of thevanes 190 a and 190 b relative to the airflow traversing through thehigh pressure compressor 164 is denoted as α, and the set of angles forthe vane rows 190 a and 190 b is denoted as a boldface α. The vanes 190a and 190 b can be rotated to a set of angles α to restrict the airflowtraversing through the LP turbine 184 relative to a non-restrictedcondition, which will be described further hereinbelow.

Each row of the blades 192 in the LP turbine 184 transmits torque to thesame shaft. The blades 192 may transfer torque to the shaft directly,through any sort of structure, through use of gears, or by any othermeans. The vanes 190 a and 190 b can be rotated to change the directionand/or the amount of the gas flow entering the blades 192. The directionand/or amount of gas flow into the blades 192 affect the torquetransmitted by the blades 192 to the LP shaft 166. Stated differently,the angle of each row of the vanes 190 a and 190 b are varied in acontrolled way to affect the total torque transmitted by the LP turbine184 to the LP shaft 166.

In one form the operation of the embodiment depicted in FIG. 3 proceedsas follows. Consider operating condition “A” in which relatively littleLP turbine torque, T_(A), is transmitted to the LP shaft 166, and the LPturbine vanes 190 a and 190 b are set at angles that approximatelyoptimize the LP turbine efficiency. Designate this set of vane anglescollectively as α_(A). The speeds of the higher pressure spools in theengine are known, and in the illustrative embodiment this only includesthe HP spool as there is no intermediate spool. For example, the HPspool rotates at known speed NHP_(A). Now consider operating condition“B” in which more LP turbine torque, T_(B), is transmitted to the LPshaft 166 than in condition “A” (T_(B)>T_(A)). Suppose again that the LPvanes 190 a and 190 b are set at angles α_(B) that approximatelyoptimize the LP turbine efficiency, and that the speeds of the higherpressure spools at this condition are again known. The HP spool speed,designated at condition “B”, is NHP_(B). Condition “B” also requiresmore fuel flow than condition “A”. The discussion herein assumes thatsustained high torque transfer from the LP turbine to the LP shaftrequires a higher HP spool rotational speed than is required for lowtorque transfer to the LP shaft. Therefore, NHP_(B)>NHP_(A).

Suppose the engine is operating at condition “A”, but a rapid transitionto condition “B” is anticipated. Before the transition is actuallyrequired, the fuel flow to the combustor 154, the angle of the LPturbine vanes 190 a and 190 b, and any other controlled engineparameters are varied together such that the fuel flow increases but thetotal LP turbine torque transmitted to the LP shaft 166 remainsapproximately constant at the level corresponding to condition “A”.Controlled parameters are varied in this way until the other spoolsreach approximately their speeds corresponding to condition “B”, or asnear as stress considerations or other operational limits allow. Forexample, the fuel flow and the LP turbine vane angles are controlledsuch that the HP spool is rotating at or near speed NHP_(B), but thetorque transmitted by the LP turbine to the LP shaft is T_(A). Othercomponents and/or parameters can be used in addition or alternative tothe components and/or parameters listed herein. Furthermore, a varietyof combinations of the components and/or parameters can be used, and notstrictly the groupings listed above. The engine can be considered to bein a standby mode for condition “B”, with the LP turbine vane angleshaving values collectively designated α_(standby). When the transitionfrom T_(A) to T_(B) is required, the LP turbine vane angles are rapidlytransitioned to angle set α_(B) while the fuel flow and any othercontrolled parameters are adjusted as required to achieve condition “B”.This transition from T_(A) to T_(B) can be accomplished rapidly becausethe high pressure spools are already rotating at or near their requiredspeeds (the HP spool is already rotating at NHP_(B), for example). Theprocedure can be reversed when a rapid decrease in power, as from T_(B)to T_(A), is required.

The various embodiments described above allow more rapid changes inpower delivered by the LP turbine 184 to the LP shaft 166 than can beachieved with an ordinary gas turbine engine. The embodiments utilizethe variable LP turbine vanes 190 a and 190 b to reduce the torquetransferred by the LP turbine 184 to the LP shaft 166 while the rest ofthe gas turbine engine 150 operates at speeds corresponding to a highpower condition. The transition from a low power condition to a highpower condition can thus be achieved without the time required foracceleration of the higher pressure spools.

In alternative embodiments, the independently movable vanes 190 a and190 b of the LP turbine 184 may be used in conjunction withindependently movable vanes of the HP compressor, much like the vanes 74a, 74 b, and 74 c described above. Additionally and/or alternatively,the independently movable vanes 190 a and 190 b can be used inconjunction with a compressor bleed and/or inlet guide vanes similar tothose structures described above with respect to FIGS. 1 and 2.

FIG. 4 depicts an embodiment of the gas turbine engine 150 of FIG. 3configured to provide power to an external load 194 through a generator193. In one application the external load 194 takes the form of adirected energy weapon. In this embodiment, the gas turbine engine 150is configured as a turboshaft engine and has only the HP compressor 164,the combustor 154, the HP turbine 182, and the LP turbine 184. Othertypes of gas turbine engines, other than a turboshaft, can also beutilized to drive the directed energy weapon 194. In addition, otherembodiments may include more spools than the LP and HP spools depictedin FIG. 4.

The generator 193 is coupled to the LP shaft 166 of the gas turbineengine 150 and provides electrical power to the directed energy weapon194 upon rotation of the LP shaft 166. The generator 193 is capable ofproducing any form of electrical power, whether direct current (DC) oralternating current (AC). Furthermore, the generator 193 may be drivenby any shaft or drive mechanism coupled to the gas turbine engine 150,not just via the LP shaft 166 as depicted in the illustrated embodiment.The generator 193 may provide a range of power at a variety ofrotational speeds of the LP shaft 166. Though not depicted in theillustrative embodiment, other mechanical devices such as gearing or aclutch assembly may be provided between the generator 193 and the LPshaft 166.

The directed energy weapon 194 receives electrical power provided fromthe generator 193 and converts it to radiant electromagnetic energyoutput. An antenna or other radiator may be included in the directedenergy weapon 194 to provide for the radiant energy output. In one form,the directed energy weapon 194 is a form of a gyrotron that generates adirected, radiant electromagnetic output in the microwave range. Inother forms, the directed energy weapon 194 may be based on a form oflaser, such as a free electron laser, that may extend from the microwaveregime to the visible light spectrum. The directed energy weapon 194 mayalso be a combination of different radiant energy generators.

The operation of the embodiment depicted in FIG. 4 proceeds as follows.The gas turbine engine 150 drives the electrical generator 193 viarotation of the low pressure spool 166. A controller (not shown) for thegenerator 193 may maintain an approximately constant mechanical rotationspeed for the LP shaft 166. At idle power, no net electrical power isproduced by the generator 193, and the HP spool rotates at a relativelylow speed compared to its design point. The LP turbine vanes 190 a and190 b may be varied in the setting angle with a mechanism similar tothat used to vary the setting angle of HP compressor vanes in theembodiments of FIGS. 1 and 2 above. At least a few seconds before thedirected energy weapon 194 is to be energized, the engine is placed in astandby mode. The generator 193, the fuel flow to the combustor 154, andthe LP turbine vane angles α are controlled together to produce an HPspool speed corresponding to full power operation while producing onlyidle power to the electrical generator. To energize the directed energyweapon 194, the required electrical power is drawn from the generator193, the LP turbine vanes 190 a and 190 b are moved to their designvalue, and fuel flow is adjusted as required to maintain the powerrequired by the generator. To de-energize the directed energy weapon194, the electrical power drawn from the generator 193 is interrupted,the LP turbine vanes 190 a and 190 b are moved to their standbyposition, and the fuel flow is adjusted as required to maintain aconstant HP spool speed. To return the engine to idle, the fuel flow isreduced and the LP turbine vane angles α are adjusted until the normalidle configuration is achieved.

FIG. 5 depicts an embodiment of a gas turbine engine 250 that includesheaters powered by a low pressure turbine and that are disposeddownstream of a compressor to provide for heat addition to an airflow.The heat addition can either be a supplement or a replacement of theheat addition by the combustion of a fuel/air mixture in a combustor.The gas turbine engine 250 of the illustrative embodiment is configuredas an aircraft power plant.

The gas turbine engine 250 includes a high pressure compressor 264, acombustor 254, a high pressure turbine 282, and a low pressure turbine284 which together produce mechanical power to drive a generator 293.The generator 293 converts the mechanical power to electrical powerwhich is used to power a heater 257 and a Primary Load device which isdepicted as a directed energy weapon 294 in the illustrated embodiment,but may be an embodiment with just a heater and no directed energyweapon. In some applications the Primary Load can take the form of otherexternal energy consuming devices, just as in any of the otherembodiments depicting an external load or Primary Load. Power can bearbitrarily shared and/or switched between the Primary Load directedenergy weapon 294 and the heater 257 through a circuit 259, the detailsof which are described hereinbelow.

The gas turbine engine 250 includes two engine spools: a high pressurespool and a low pressure spool. It will be appreciated, however, thatany number of other spools may also be provided in other embodiments.The high pressure spool includes the high pressure compressor 264, ahigh pressure shaft 268, and the high pressure turbine 282. Unlike thehigh pressure spool, the low pressure spool in the illustrativeembodiment includes only a low pressure shaft 266 and the low pressureturbine 284.

The generator 293 is coupled to the LP shaft 266 of the gas turbineengine 250 and, upon rotation of the LP shaft 266, provides electricalpower to the circuit 259, and thus selectively to the directed energyweapon 294 and the heater 257. The generator 293, just as in thegenerators discussed in various embodiments hereinabove, is capable ofproducing any form of electrical power, whether direct current (DC) oralternating current (AC). Furthermore, the generator 293 may be drivenby any shaft of the gas turbine engine 250, not just via the LP shaft266 as depicted in the illustrated embodiment. The generator 293 mayprovide a range of power at a variety of rotational speeds of the LPshaft 266. Though not depicted in the illustrative embodiment, othermechanical devices such as gearing or a clutch assembly may be providedbetween the generator 293 and the LP shaft 266.

The combustor 254 is arranged as an annular combustor in the illustratedembodiment but may take on different forms in other embodiments, such asa can-annular configuration to set forth just one non-limiting example.The combustor 254 mixes air with fuel delivered from a fuel control 255and burns the mixture to produce heat needed for continued engineoperation. The fuel control 255 determines the flow rate for fueldelivery based upon operating conditions, among other possible factors.

The heater 257 is powered by the generator 293 and positioned downstreamof the compressor 264 and upstream of the combustor 254. When activated,the heater 257 is capable of heating combustion air prior to entry intothe combustor 254. In other embodiments, the heater 257 could bepositioned anywhere between the HP compressor 264 and the LP turbine284. As used herein, the term “combustion air” means any gas whether ornot the primary heat-producing process of the engine is combustion, andwhether or not the gas can be considered air. As will be appreciated,use of the heaters within an engine associated with a military vehiclewill not necessarily increase the infrared signature made by thevehicle, since the heat addition provided by the heater 257 may beoffset by a reduction in fuel delivered to the combustor 254 and thus areduction in heat produced by combustion. The heater 257 can be arrangedas a single heater or an array of heaters, and furthermore may be adiffuse set of heating elements annularly distributed upstream of thecombustor 254. The heater 257 includes any mechanism that allowselectrical energy to be used to produce and transfer heat to thecombustion air and includes such techniques as resistive heating,radiation heating, and the production of plasma.

The circuit 259 is capable of allocating power in selectable quantitiesbetween the Primary Load, depicted as the directed energy weapon 294,and the heater 257. The directed energy weapon 294 can take the form ofthe directed energy weapon embodiments described above. A rheostat 261is used to select the desired power sharing arrangement in theillustrative embodiment. Though not depicted in FIG. 5, one or moreswitches and/or circuit breakers may be used to sever the powerdelivered to either the directed energy weapon 294 or the heater 257.Various other circuit arrangements are contemplated herein to shareand/or distribute power. The circuit 259 may be operated manually orautomatically, and may result in either step changes to the powersharing arrangement or any other variable changes that may not bereadily predictable. The power may be dynamically allocated on the basisof current operational needs of the gas turbine engine 250, the tacticalenvironment that the directed energy weapon 294 is operating within, orany other consideration. In some applications, excess power not neededby the directed energy weapon 294 may be diverted to the heater 257. Forexample, excess energy may be diverted whenever the directed energyweapon 294 is not engaged with a target, to set forth just onenon-limiting example.

The directed energy weapon 294 receives electrical power provided fromthe generator 293 and converts it to radiant electromagnetic energyoutput. An antenna or other radiator may be included in the directedenergy weapon 294 to provide for the radiant energy output. In one form,the directed energy weapon 294 is a form of a gyrotron that generates adirected, radiant electromagnetic output in the microwave range. Inother forms the directed energy weapon 294 may be based on a form oflaser, such as a free electron laser, that may extend from the microwaveregime to the visible light spectrum. The directed energy weapon 294 mayalso be a combination of different radiant energy generators.

In one non-limiting form the operation of the gas turbine engine 250 canbe described as follows. A two-spool gas turbine engine 250 is used toprovide electrical power for a directed energy weapon 294 by driving anelectrical generator 293 connected to its low-pressure (LP) spool. Thedirected energy weapon 294 can take the form of the directed energyweapon embodiments described above. A controller (not shown) for thegenerator 293 maintains an approximately constant mechanical rotationspeed for the LP shaft 266. At idle power, no electrical power isproduced by the generator 293, and the HP spool rotates at a relativelylow speed compared to its design point. At least a few seconds beforethe directed energy weapon 294 is to be energized, the engine is placedin a standby mode. The generator 293 and the engine fuel flow arecontrolled to produce the full electrical power required by the directedenergy weapon 294. All of this power, however, is directed to resistiveheating elements between the HP compressor exit and the combustor inlet.These heat the air entering the combustor 254, reducing the amount offuel that must be burned to produce the power being absorbed by thegenerator 293. In some forms of the present application the generator293 may not produce all of the power required. The HP spool acceleratesto the rotational speed required to sustain the new level of the LPshaft power. To energize the directed energy weapon 294, the electricalpower is switched from the heating elements to the directed energyweapon. This provides nearly instantaneous power to the directed energyweapon, and requires no change in the rotational speed of the HP spool.The engine control increases the fuel flow to the combustor 254 as theheating elements cool to maintain a constant power delivery to thegenerator 293. To de-energize the directed energy weapon, the electricalenergy is again switched to the heating elements. As long as the engineis to remain in standby mode, the engine control regulates the fuel flowto maintain constant power delivery to the generator 293. The return theengine to idle, the fuel flow is reduced causing a reduction in powerdelivered to the generator 293, a reduction in electrical powerdelivered to the heating elements, and less energy released by theheating elements to the engine cycle. In one form the engine and thegenerator 293 controls work together to maintain a constant LProtational speed while the engine is returned to idle, at whichcondition no electrical power is delivered to the heating elements.

Turning now to FIG. 6, the invention applies to a gas turbine engine 350with more than one system of rotating shafts. Each system typicallyconsists of a compressor 364 connected via a shaft 360 to a turbine 356.Each system is free to rotate at a speed different than that of theother systems, although devices, either mechanical, electrical, orotherwise, may transfer power from one shaft to another. The systeminvolving the highest pressures at the compressor exit and the turbineinlet is referred to as the high-pressure, or HP, spool. Any number ofrotating shaft systems may exist, and could be distinguished byterminology such as a high-pressure spool, an intermediate-pressurespool, a low-pressure spool, and so on. In one form the presentapplication provides extracting power from a lower pressure system andapplying it to one or more of the higher pressure spools. To set forthjust a few non-limiting examples, the present application can provideextracting power from an LP spool and applying it to the HP spool, orextracting it from an intermediate pressure (IP) spool and applying itto the HP spool. If power is drawn from the lowest pressure system, orLP spool, it applies both to LP spools having a compressor 362 and aturbine 384 (an example being the LP spool of turbofan engines) and toLP spools having only a turbine 384 (an example being the LP spool ofturboprop and turboshaft engines). The turbine component of this LPspool is herein referred to as the LP turbine 384 and the shaft as theLP shaft 366. The discussion below assumes that sustained high torquetransfer from the LP turbine 384 to the LP shaft 366 requires higherrotational speeds of the other spools than is required for low torquetransfer to the LP shaft 366. For example, high torque transfer from theLP turbine 384 to the LP shaft 366 can only be achieved at a high HPspool speed, whereas low torque transfer from the LP turbine 384 to theLP shaft 366 can be achieved at a low HP spool speed. This is trueregardless of the speed of the LP spool under high or low torquetransfer.

Consider operating condition “A” in which relatively little LP turbinetorque, T_(A), is transmitted to the LP shaft, and condition “B” inwhich more LP turbine torque, T_(B), is transmitted to the LP shaft thanin condition “A” (T_(B)>T_(A)). Suppose the engine is operating atcondition “A”, but a rapid transition to condition “B” is anticipated.Before the transition is actually required, the engine is controlled asnecessary to cause more torque to be transmitted from the LP turbine tothe LP shaft. Any excess power beyond that of condition “A”, however, istransferred to one or more of the higher pressure spools. This powertransfer can be accomplished by electrical, mechanical, or other means.The transfer of power causes the spool(s) to which it is transferred toaccelerate. The end goal is to achieve a state in which the speed of theLP spool and the net torque transfer of the LP turbine to the LP shaftis about that of condition “A” but the speeds of the other spools areapproximately those of condition “B”. The engine can be considered to bein a standby mode for condition “B”. The transfer from T_(B) to T_(A)can be accomplished rapidly because the high pressure spools are alreadyrotating at or near their required speeds. The procedure can be reversedwhen a rapid decrease in power, as from T_(B) to T_(A), is required.

In one non-limiting example, a two-spool turboshaft gas turbine engine350 is disclosed in FIG. 6 and is used to provide electrical power foran energy device 394, depicted in the illustrative embodiment as adirected energy weapon 394, by driving an electrical generator 393connected to its low-pressure (LP) spool. In other applications theenergy device 394 can take other forms. The directed energy weapon 394can take the form of the directed energy weapon embodiments describedabove. A controller (not shown) for the generator 393 maintains anapproximately constant mechanical rotation speed for the LP shaft 366.At idle power, no net electrical power is produced by the generator 393,and the HP spool rotates at a relatively low speed compared to itsdesign point. An electric motor 395 is connected to the HP spool througha gearbox 396, but is supplying no power to the spool at the idlecondition. At least a few seconds before the directed energy weapon 394is to be energized, the gas turbine engine 350 is placed in a standbymode. The generator 393 and the engine fuel flow are controlled togetherto produce electrical power through the LP generator 393, but this poweris directed to the HP motor 395 and used to accelerate the HP spool.Enough power is generated to achieve full design speed on the HP spool.In some forms, however, insufficient power may be generated. To energizethe directed energy weapon 394, the electrical power directed to the HPmotor 395 is instead directed to the directed energy weapon 394, andcontrolled engine parameters (such as fuel flow) are adjusted to supplythe power required by the directed energy weapon 394. To de-energize thedirected energy weapon 394, its electrical power is redirected to the HPmotor 395, and engine control parameters adjusted to maintain constantHP spool speed. To return the engine to idle, the fuel flow is reducedso that power to the HP motor 395 also decreases until the normal idleconfiguration is achieved. A second example is like that describedabove, but with a continuous slipping clutch providing power transferfrom the LP spool to the HP spool rather than an electric motorconnected to the HP spool.

One aspect of the present application provides a gas turbine engine thatincludes a high pressure compressor having a plurality of rows ofindependently movable variable vanes. Each row of the plurality of rowsof independently movable vanes can be set at a unique angle relative toan axis of rotation of the compressor. For example, a row of variablevanes in a first stage of the compressor may be set at an angledifferent from a row of variable vanes in a second stage of thecompressor. In one mode of operation, the plurality of rows of vanes canbe oriented to reduce the flow capacity of the compressor at a givenspeed. The fuel flow to the combustor is adjusted to maintainapproximately the same supply of energy to components downstream of theturbine driving the compressor. This mode may be referred to as“standby” and is characterized by an increase in speed of thecompressor. A compressor bleed or variable inlet guide vanes can also beused to supplement the vanes in achieving the desired effect. It will beappreciated that the engine may not be operating in an optimal settingin this configuration. If an increase in torque output is desired in alow pressure turbine of the gas turbine engine in a second mode ofoperation, then the vanes are repositioned to allow more flow throughthe compressor. The onset of the increased torque in this configurationmay be better understood by contrast to a conventional gas turbineengine.

If a conventional gas turbine were operating in a normal mode ofoperation when an increase in torque output is desired and/or commanded,then the gas turbine would likely need to accelerate a high pressurecompressor to a higher speed to achieve such an increase, whichsometimes requires an undesirable “spool up” time that varies dependingon the rotational inertia of the high pressure spool, among otherthings. In the instant application, however, the high pressurecompressor need not be accelerated to a higher speed since it is alreadyat the speed required for the high torque condition. Therefore, thetorque output of the low pressure turbine is increased without anassociated need to increase the speed of the high pressure compressor.In some embodiments, the increase in torque can occur rapidly.

A directed energy weapon can be coupled to the gas turbine engine andcan be powered using the techniques described above. For example, thedirected energy weapon could be placed in a standby mode and thenrapidly powered by a change in configuration of the vanes.

Another aspect of the present application provides a gas turbine enginethat includes a low pressure turbine having a plurality of rows ofindependently movable variable vanes. Each row of the plurality of rowsof independently movable vanes can be set at a unique angle relative toan axis of rotation of the turbine. In one mode of operation, theplurality of rows of vanes can be positioned such that while the fuelflow to the combustor may be increased, the total low pressure turbinetorque transmitted to a shaft remains approximately constant. Theincrease in the fuel flow accelerates a high pressure compressor to arotational speed at or near the speed required for sustained high torqueoutput from the low pressure turbine. This mode of operation maysometimes be referred to as “standby.” In this configuration, the enginemay not be operating in an optimal setting. In a second mode ofoperation, if an increase in torque output is subsequently desired inthe low pressure turbine then the vanes are repositioned to produce moretorque. If the gas turbine were operating in a normal mode of operationwhen an increase in torque output is desired and/or commanded, then thegas turbine might need to accelerate the high pressure compressor to ahigher speed. In the instant application, however, the compressor neednot be accelerated to a higher speed since it is already at the speedrequired for the high torque condition. Therefore, the torque output ofthe low pressure turbine is increased without an associated need toincrease the speed of the high pressure compressor. In some embodiments,the increase in torque can occur rapidly.

A further aspect of the present application provides a gas turbineengine having a generator connected to a low-pressure spool. At idlepower, the generator produces no net electrical power and ahigh-pressure spool in the gas turbine engine rotates at a relativelylow speed compared to its design point. An electric motor is connectedto the high pressure spool through a gearbox but provides no power tothe spool. The engine can be placed in a standby mode wherein thegenerator and the engine fuel flow are controlled to produce electricalpower as the engine is accelerated. The electrical power is provided tothe motor to assist in accelerating the high pressure spool to its fulldesign speed faster than simply fueling alone. Once at the full designspeed, the power output of the generator can be re-routed to providepower to a directed energy weapon, wherein controlled engine parameterssuch as the fuel flow may be further adjusted to account for the newconfiguration. Likewise, electrical power from the generator can beredirected to power the motor when the directed energy weapon isde-energized. The controlled engine parameters may again be adjusted toaccount for the change in configuration. To return the engine to idle,the fuel flow may be reduced which results in a corresponding reductionin power to the high pressure spool.

Yet another aspect of the present application provides a gas turbineengine having a turbine that provides power to a generator. Thegenerator can be selectively configured to provide power to an externaldevice, such as a directed energy weapon, or may provide power toheaters positioned downstream of a compressor and upstream of acombustor in the gas turbine engine. The heaters are configured toprovide heat addition to the air stream entering the combustor. In thismode of operation, the turbine produces more power than is needed at themoment by the load connected to the generator. The direction of theexcess energy to the heaters permits a reduction of fuel flow andestablishes a standby mode for increased power demand from thegenerator. The engine is able to quickly respond to increased powerdemand from the generator by directing energy from the heaters to theload and increasing fuel flow as necessary.

One embodiment of the present application provides a system forproviding rapid changes in output torque comprising a first operatingmode which configures a gas turbine engine to operate at a firstoperating point having a first rotational speed of a compressor and afirst torque output of a turbine, and a second operating mode whichpositions a plurality rows of independently movable variable vaneswithin the gas turbine engine, wherein a second speed of the compressoris substantially the same as the first speed and a second torque outputof the turbine is higher than the first torque output.

One feature of the present application provides wherein the plurality ofrows of independently movable variable vanes are in a high pressurecompressor of the gas turbine engine.

Another feature of the present application provides wherein the secondoperating mode includes operating a bypass conduit to convey compressedair away from a core flow of the gas turbine engine.

Yet another feature of the present application provides wherein thesecond operating mode includes positioning a plurality of variable inletguide vanes to the compressor.

Still another feature of the present application provides wherein thegas turbine engine is a multi-spool engine and the compressor isconnected to a higher pressure spool than the turbine.

Yet a further feature of the present application provides wherein acontroller is configured to provide the first operating mode and thesecond operating mode.

Still yet a further feature of the present application provides adirected energy weapon, wherein the directed energy weapon is energizedafter the gas turbine engine is commanded to the second operating mode.

Another embodiment of the present application provides a methodcomprising positioning a plurality of rows of variable vanes of a gasturbine engine, wherein at least two of the plurality of rows areindependently movable, powering the gas turbine engine to rotate acompressor at a first speed and provide a torque output of a turbine,and providing an increase in torque output of the turbine whilemaintaining substantially the same rotational speed of the compressor byrepositioning the plurality of rows of variable vanes.

One feature of the present application provides wherein the plurality ofrows of variable vanes are in a high pressure compressor of the gasturbine engine.

Another feature of the present application provides venting airflow fromthe compressor.

Still another feature of the present application provides positioning aplurality of variable inlet guide vanes to the compressor.

Still a further feature of the present application provides powering thegas turbine engine includes controlling one or more of the plurality ofrows of independently movable variable vanes, an engine fuel flow, andthe venting airflow.

Yet still a further feature of the present application provides whereinthe gas turbine engine includes a high pressure spool and a low pressurespool, and wherein the compressor is a high pressure compressor and theturbine is a low pressure turbine.

Still yet another feature of the present application provides driving anelectrical generator from a shaft connected to the turbine.

Still another feature of the present application provides operating adirected energy weapon after the providing an increase in torque outputof the turbine.

A further embodiment of the present application provides a system forproviding rapid changes in output torque comprising a first operatingmode which configures a gas turbine engine to operate at a firstoperating point having a first rotational speed of a compressor and afirst torque output of a turbine, and a second operating mode whichpositions movable variable vanes within a turbine of the gas turbineengine, wherein a second speed of the compressor is substantially thesame as the first speed and a second torque output of the turbine ishigher than the first torque output.

A feature of the present application provides wherein the gas turbineengine includes a plurality of rows of movable variable vanes.

Another feature of the present application provides wherein movablevariable vanes are in a low pressure turbine of the gas turbine engine.

Still another feature of the present application provides wherein thegas turbine engine is a multi-spool engine and the compressor isconnected to a higher pressure spool than the turbine.

Still a further feature of the present application provides wherein acontroller is configured to provide the first operating mode and thesecond operating mode.

Still yet another feature of the present application provides a directedenergy weapon, wherein the directed energy weapon is energized after thegas turbine engine is commanded to the second operating mode.

Yet a further embodiment of the present application provides a methodcomprising positioning variable vanes within a turbine of a gas turbineengine, powering the gas turbine engine to rotate a compressor at afirst speed and provide a torque output of the turbine, and providing anincrease in torque output of the turbine while maintaining substantiallythe same rotational speed of the compressor by repositioning thevariable vanes.

A feature of the present application provides wherein the turbineincludes a plurality of rows of variable vanes.

Another feature of the present application provides wherein powering thegas turbine engine includes controlling one or more of the variablevanes and an engine fuel flow.

Still another feature of the present application provides wherein thegas turbine engine includes a high pressure spool and a low pressurespool, and wherein the compressor is a high pressure compressor and theturbine is a low pressure turbine.

Still yet another feature of the present application provides driving anelectrical generator from a shaft connected to the turbine.

Still a further feature of the present application provides operating adirected energy weapon after the providing an increase in torque outputof the turbine.

Yet another embodiment of the present application provides an apparatuscomprising a gas turbine engine having a combustor and a turbine, and aheater positioned upstream of the combustor and configured to heat anincoming air flow into the combustor, wherein the turbine is used toprovide power to the heater.

A feature of the present application provides wherein the turbine is alow pressure turbine.

Another feature of the present application provides a generator coupledwith a shaft that rotates with the turbine, wherein the generatorsupplies power to the heater.

Yet another feature of the present application provides a directedenergy weapon coupled with the generator, wherein power from thegenerator is selectively applied either to the directed energy weapon orthe heater.

Still yet another feature of the present application provides a fuelcontrol that offsets a fueling to the combustor when the incoming air tothe combustor is heated by the heater.

Still a further feature of the present application provides wherein theheater includes electrical heating elements.

One form of the present application provides a method comprisingoperating a heater positioned upstream of a combustor of a gas turbineengine, wherein the heater selectively heats incoming air to thecombustor and is powered by a turbine of the gas turbine engine.

A feature of the present application provides diverting power from theheater and supplying a diverted power to a directed energy weapon.

Another feature of the present application provides wherein an energydemand from the directed energy weapon is varying, and wherein thediverting power is varying.

Yet still another feature of the present application provides reducing afuel delivery to the combustor when the heater is operating.

Still yet another feature of the present application provides whereinthe turbine supplies mechanical power to a generator, and the generatorsupplies electrical power to the heater.

Another form of the present application provides a method comprisingallocating power derived from a turbine to selectively heat an incomingairflow to a combustor or operate a directed energy weapon.

A feature of the present application provides wherein the allocatingpower is dynamic.

Another feature of the present application provides generatingelectricity from the power derived from the turbine, wherein theelectricity is used to selectively heat the incoming airflow to acombustor or to operate the directed energy weapon.

A further form of the present application provides a method comprisingpositioning a heater within a gas turbine engine downstream from acompressor and upstream from a combustor, wherein the heater is poweredby a turbine.

One feature of the present application provides wherein the allocatingpower is dynamic.

Another feature of the present application provides coupling a directedenergy weapon to the gas turbine engine.

Yet another feature of the present application provides coupling agenerator to the turbine, wherein the generator provides electricity tothe heater and to the directed energy weapon.

Yet a further form of the present application provides an apparatuscomprising a gas turbine engine having a compressor and a turbine, and aprime mover coupled to the compressor and capable of being powered bythe turbine, wherein the compressor can be accelerated by the primemover.

A feature of the present application provides wherein a spool thatdrives the compressor is higher pressure than a spool that is driven bythe turbine.

Another feature of the present application provides a generator coupledto the turbine, wherein the generator provides power to the prime mover.

Still another feature of the present application provides a directedenergy weapon capable of being powered by the gas turbine engine.

Yet still another feature of the present application provides wherein agenerator coupled to the turbine is capable of providing power to thedirected energy weapon.

Yet another form of the present application provides a method comprisingcoupling a prime mover to a compressor within a gas turbine enginewherein the power that energizes the prime mover originates from theturbine.

One feature of the present application provides coupling a generator tothe turbine, wherein the generator provides electricity to energize theprime mover.

Another feature of the present application provides wherein thecompressor is rotates with a higher pressure spool than the spool thatrotates with the turbine.

One feature of the present application provides a method comprisingoperating a gas turbine engine at a first compressor speed, acceleratinga spool of the gas turbine engine through the motive power of a primemover, wherein the prime mover receives power from a turbine, anddirecting power from the prime mover to a directed energy weapon at asecond compressor speed.

A feature of the present application provides coupling a generator tothe turbine, wherein the generator provides electricity to energize theprime mover.

Another feature of the present application provides wherein no power isprovided to the prime mover at the first compressor speed.

Yet another feature of the present application provides providing a fuelto a combustor to accelerate the spool of the gas turbine engine.

Still another feature of the present application provides wherein theprime mover is electrical or mechanical.

Another feature of the present application provides an apparatuscomprising a gas turbine engine having at least two spools, the firstspool having a low pressure compressor and a low pressure turbine andreferred to as a LP spool, the second spool having a high pressurecompressor and a high pressure turbine and referred to as a HP spool,and a prime mover coupled to the LP spool, the prime mover capable ofgenerating work to selectively power the HP spool or a directed energyweapon.

A feature of the present application provides a gearbox coupled with anLP shaft of the LP spool and a shaft coupled between the gearbox and theprime mover.

Another feature of the present application provides a gearbox coupledwith an HP shaft of the HP spool and a shaft coupled between the gearboxand a motor, the motor driven by the prime mover.

A further feature of the present application provides a methodcomprising coupling a prime mover to a lower pressure spool of a gasturbine engine, the prime mover operable to provide energy to power ahigher pressure spool or an energy device.

A feature of the present application provides wherein the energy deviceis a directed energy weapon.

Another feature of the present application provides wherein the higherpressure spool is a high pressure spool.

Still another feature of the present application provides wherein thelower pressure spool is a low pressure spool.

Still yet another feature of the present application provides connectinga shaft and a gear box between the lower pressure spool and the primemover.

Yet a further feature of the present application provides a methodcomprising operating a gas turbine engine, the gas turbine engine havinga first pressure spool and a second pressure spool, wherein the firstpressure spool operates at a lower pressure than the second pressurespool; and selectively providing power from a prime mover to either thesecond spool or a directed energy weapon.

A feature of the present application provides wherein the selectivelyproviding power includes providing power to the second spool at a firstspeed, and providing power to the directed energy weapon at a secondspeed.

In one form a gas turbine engine is provided having variable vanes in adownstream location of an HP compressor. The vanes can be used to placethe gas turbine engine in a standby mode by reducing the flow capacityof the compressor. Engine fueling can be controlled to maintain outputtorque of an LP system. When an increase in torque is required, thevariable vanes can be repositioned to increase a flow through thecompressor. In another form, a gas turbine engine is provided havingvariable vanes in an HP turbine. The vanes can be used to place the gasturbine engine in standby mode with an associated change in enginefueling. When an increase in torque of the LP system is desired, thevariable vanes can be repositioned. In yet another form, a gas turbineengine includes an LP shaft that can selectively drive a primary loadand/or an electrical generator. Power from the generator can be used topower heating elements positioned in or upstream of the combustor. Whenpower is not required to drive the primary load, the electricalgenerator can be used to power the heating elements to reduce fuelconsumption in a standby mode. In still another form, a gas turbineengine includes an LP shaft that drives an electrical generator. Thegenerator can power an electric motor which can selectively drive an HPspool. To enter a standby mode of operation, the electric motor canincrease rotational speed of the HP spool.

Still yet another aspect of the present application includes anapparatus comprising a gas turbine engine having a shaft connectingturbomachinery components, a rotatable bladed component including rowsof movable vanes, and an engine controller operable to provide for aplurality of engine operating conditions including: a first operatingcondition in which a plurality of the rows of movable vanes have a firstposition, the shaft operates at a first rotational speed, and the gasturbine engine provides a first torque output, a standby condition inpreparation of transitioning from the first operating condition to asecond operating condition in which the plurality of the rows of movablevanes have a standby position, the shaft operates at a standbyrotational speed greater than the first rotational speed and the gasturbine engine provides a standby torque output, and wherein in thesecond operating condition the plurality of the rows of movable vaneshave a second position, the shaft operates at a second rotational speedgreater than the first rotational speed and the gas turbine engineprovides a second torque output greater than the first torque output.

A still further aspect of the present application includes a methodcomprising transitioning from a low output controller configuration to ahigh output controller configuration by: positioning at least two rowsof variable vanes of a gas turbine engine rotatable component to alter aflow capacity of the rotatable component relative to the low outputcontroller configuration, in conjunction with the positioning, poweringthe gas turbine engine to rotate a shaft at a first speed and provide atorque output of a turbine, and generating an increase in torque outputof the turbine while achieving substantially the same rotational speedof the shaft by repositioning the at least two rows of variable vanes.

Yet another aspect of the present application includes a methodcomprising operating a gas turbine engine including rotating aturbomachinery component at a first rotational speed, positioningvariable vanes on opposite sides of rotating blades of the gas turbineengine to a changed airflow position relative to a position during theoperating, associated with the positioning, delivering an energy to thegas turbine engine to provide for a second rotational speed of theturbomachinery component higher than the first rotational speed,re-positioning the variable vanes after the delivering, and increasing atorque output of the gas turbine engine.

Still yet a further aspect of the present application includes anapparatus comprising a gas turbine engine having a shaft associated witha relatively high pressure spool of a multi-spool engine, a turbinehaving variable vanes, and an engine controller operable to provide fora plurality of engine operating conditions including: a first operatingcondition in which the variable vanes have a first position, the shaftoperates at a first rotational speed, and the gas turbine engineprovides a first torque output, a standby condition in preparation oftransitioning from the first operating condition to a second operatingcondition in which the variable vanes have a standby position, the shaftoperates at a standby rotational speed greater than the first rotationalspeed and the gas turbine engine provides a standby torque output, andwherein in the second condition the variable vanes have a secondposition, the shaft operates at a second rotational speed greater thanthe first rotational speed and the gas turbine engine provides a secondtorque output greater than the first torque output.

A further aspect of the present application includes a method comprisingtransitioning from a low output controller configuration to a highoutput controller configuration by: positioning a plurality of variablevanes of a turbine within a gas turbine engine to a standby positionwith respect to a flow position associated with the low outputcontroller configuration, in conjunction with the positioning, poweringthe gas turbine engine to change a flow rate through the turbinerelative to the flow rate at the low output condition and provide atorque output of the turbine, and generating an increase in torqueoutput of the turbine while achieving substantially the same rotationalspeed of the shaft by repositioning the plurality of variable vanes.

A still further aspect of the present application includes a methodcomprising operating a gas turbine engine including rotating arelatively high pressure turbine at a first rotational speed,positioning a plurality of variable vanes adjacent rotating blades of arelatively low pressure turbine of the gas turbine engine to an alteredairflow position relative to a position during the operating, associatedwith the positioning, delivering an energy to the gas turbine engine toprovide for a second rotational speed of the relatively high pressureturbine higher than the first rotational speed, re-positioning thevariable vanes after the delivering, and increasing a torque output ofthe gas turbine engine.

Yet a still further aspect of the present application includes anapparatus comprising a gas turbine engine having a turbine operable toextract energy from a passing flow stream, and an energy transferringdevice coupled with the turbine and operable to receive the extractedenergy, the energy transferring device operable to selectively return atleast a portion of the extracted energy to a gas path component of thegas turbine engine or provide the extracted energy to an external energysystem.

Another aspect of the present application includes a method comprisingflowing a flow stream through a turbine of a multi-spool gas turbineengine to produce power from the rotation of the turbine, apportioningthe power produced from the turbine among operating an external energyconsuming system and operating a device within the gas turbine engine,and wherein the operating the device is one of assistingly rotating aspool shaft and heating a flow stream.

Still another aspect of the present application includes a methodcomprising generating power derived from a rotating turbine of a gasturbine engine, and allocating power derived from the turbine between anexternal primary load and an internal gas path component.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinventions are desired to be protected. It should be understood thatwhile the use of words such as preferable, preferably, preferred or morepreferred utilized in the description above indicate that the feature sodescribed may be more desirable, it nonetheless may not be necessary andembodiments lacking the same may be contemplated as within the scope ofthe invention, the scope being defined by the claims that follow. Inreading the claims, it is intended that when words such as “a,” “an,”“at least one,” or “at least one portion” are used there is no intentionto limit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary.

1. An apparatus comprising: a gas turbine engine having a shaftconnecting turbomachinery components, a rotatable bladed componentincluding rows of movable vanes, and an engine controller operable toprovide for a plurality of engine operating conditions including: afirst operating condition in which a plurality of the rows of movablevanes have a first position, the shaft operates at a first rotationalspeed, and the gas turbine engine provides a first torque output; astandby condition in preparation of transitioning from the firstoperating condition to a second operating condition in which theplurality of the rows of movable vanes have a standby position, theshaft operates at a standby rotational speed greater than the firstrotational speed and the gas turbine engine provides a standby torqueoutput; and wherein in the second operating condition the plurality ofthe rows of movable vanes have a second position, the shaft operates ata second rotational speed greater than the first rotational speed andthe gas turbine engine provides a second torque output greater than thefirst torque output.
 2. The system of claim 1, wherein the plurality ofthe rows of movable vanes are in a relatively high pressure compressorof the gas turbine engine.
 3. The system of claim 2, wherein the standbycondition includes operating a bypass conduit to convey compressed airaway from a core flow of the gas turbine engine.
 4. The system of claim1, wherein the plurality of the rows of movable vanes are in a turbineof the gas turbine engine.
 5. The system of claim 1, wherein the gasturbine engine is a multi-spool engine and the rotatable bladedcomponent is associated with a higher pressure spool than a spool thatprovides for a torque output.
 6. The system of claim 1, wherein thestandby position reduces the flow through the rotatable bladed componentrelative to the first position
 7. The system of claim 1, which furtherincludes a vehicle having the gas turbine engine and the enginecontroller.
 8. The system of claim 7, which further includes a directedenergy weapon, wherein the directed energy weapon is energized as aresult of the gas turbine engine operating at the second condition.
 9. Amethod comprising: transitioning from a low output controllerconfiguration to a high output controller configuration by: positioningat least two rows of variable vanes of a gas turbine engine rotatablecomponent to alter a flow capacity of the rotatable component relativeto the low output controller configuration; in conjunction with thepositioning, powering the gas turbine engine to rotate a shaft at afirst speed and provide a torque output of a turbine; and generating anincrease in torque output of the turbine while achieving substantiallythe same rotational speed of the shaft by repositioning the at least tworows of variable vanes.
 10. The method of claim 9, wherein the poweringincludes providing an increased flow rate of fuel to a combustor of thegas turbine engine relative to a flow rate of fuel to the combustorprior to the positioning.
 11. The method of claim 9, wherein the shaftis rotatingly coupled with one of a relatively high pressure compressorand a relatively low pressure turbine.
 12. The method of claim 9, whichfurther includes controlling the rotational rate of a relatively lowpressure turbine.
 13. The method of claim 12, wherein the controllingfurther includes providing power to a directed energy weapon after therepositioning the at least two rows of variable vanes.
 14. The method ofclaim 9, which further includes loading the gas turbine engineconcurrent with the generating an increase in torque output to maintaina substantially constant rotational rate of a relatively low pressureturbine.
 15. The method of claim 14 wherein the loading includesproducing power from an electrical generator through a shaft drivinglyconnected to the turbine.
 16. The method of claim 15 wherein the loadingincludes operating a directed energy weapon after the providing anincrease in torque output of the turbine.
 17. A method comprising:operating a gas turbine engine including rotating a turbomachinerycomponent at a first rotational speed; positioning variable vanes onopposite sides of rotating blades of the gas turbine engine to a changedairflow position relative to a position during the operating; associatedwith the positioning, delivering an energy to the gas turbine engine toprovide for a second rotational speed of the turbomachinery componenthigher than the first rotational speed; re-positioning the variablevanes after the delivering; and increasing a torque output of the gasturbine engine.
 18. The method of claim 17, which further includesreturning the variable vanes to an orientation that provides for achanged airflow position relative to a position during the positioning.19. The method of claim 18, wherein the delivering includes elevating atemperature of a flow stream delivered from a combustor of the gasturbine engine.
 20. The method of claim 19, wherein the increasingincludes boosting a fuel flow rate to the combustor.
 21. The method ofclaim 17, which further includes powering a directed energy weapon as aresult of the increasing.
 22. The method of claim 21, which furtherincludes depowering the directed energy weapon.
 23. The method of claim22, wherein the turbomachinery component is a compressor and thedepowering includes decreasing a speed of the compressor from the secondrotational speed to the first rotational speed. 24.-76. (canceled)